The longterm goal of this project, as it has been for 30 years, is the prevention or control of trachoma and other Chlamydia trachomatis infections of the eye. The goal is sought through better understanding of the pathogenesis, immunology and epidemiology of the infections, and through basic studies of the microorganisms. The aim of the studies has been toward immunological prevention or control rather than treatment. This application proposes to exploit recent findings of glycoproteins and lectins on the Chlamydia trachomatis elementary body. Investigations will be undertaken of their role in infection of mammalian host cells at the molecular and cellular level. The attachment of the microorganism to the cell and invasion of the cell to initiate the infectious process will be analyzed. Antigens on the organism and the receptors on the host cell membrane involved in this infectious process will be isolated and characterized. The effect of inhibition of protein glycosolation of the organism on C. trachomatis attachment and infectivity will be determined. The structure of the glycan portion of the glycoproteins of C. trachomatis will be studied with the goal of producing synthetic glycans for functional and immunological studies. Monoclonal and polyclonal antibodies against the carbohydrate determinants will be prepared in order to support studies on: 1) Immunogold staining of surface antigens of the organism, 2) binding of glycans to eukaroytic cells, and 3) neutralization of cell culture infection. Video cinematographic studies of Chlamydia growth in primary conjunctival cell culture with newly available higher powered light microscopy will allow observation of organism and cell interactions at the initiation of the infectious cycle and the effect of antibodies and other treatments on infection. Cloning of genes encoding glycoproteins of C. trachomatis will be undertaken with the goal of producing these antigens by recombinant techniques. Standard techniques will be utilized to search for lectins in the Chlamydia elementary bodies. Host cell receptors involved in Chlamydia attachment will be isolated and their chemical structures determined. This will allow localization of the receptors and studies of their biological function. Cloning of the receptor genes will bc attempted. Two other protein antigens of C. trachomatis, the 155 kDa species-specific antigen and the 75 kDa genus-specific heat shock protein will be studied for their potential as antigens for the prevention of infection. Immunization studies in animal models (mice and monkeys) will be undertaken when appropriate antigens have been identified and produced in quantity.